1. Field of the Invention
This invention relates to catalysis. In one aspect, the invention relates to the catalytic manufacture of aryl hydroperoxides from corresponding aryl compounds while in another aspect, the invention relates to specific catalysts useful in this manufacture.
2. Description of the Prior Art
The oxidation of aryl compounds to form aryl hydroperoxides is known generally. For example, the first step in a widely practiced process for manufacturing phenol is the oxidation of cumene to cumene hydroperoxide and was first demonstrated by Hock and Lang, Chem. Ber., 77B, 257, in 1944. Since that time many improvements have been made as illustrated by U.S. Pat. No. 2,547,938 (use of base, emulsifying agent and initiator), U.S. Pat. No. 2,973,310 (use of hydrogen bromide or a bromene salt as a catalyst), U.S. Pat. No. 3,290,384 (use of alkali or alkaline earth metal salt of an oxy acid of plumbate, bismuthate, stannate or antimonate), U.S. Pat. No. 3,959,381 (using cumene hydroperoxide as an initiator), U.S. Pat. No. 4,022,841 (using organometallic complexes as catalyst), and U.S. Pat. No. 4,034,047 (using polyacrylonitrile as a catalyst).
As is evident from the preceding, much of the past research effort has been directed to the identification and development of useful hydroperoxidative catalysts. However, many prior art catalysts are not truly catalysts but are merely vehicles which provide favorable conditions for a hydroperoxidative reaction. For example, the addition of base to the reaction mixture removes the organic acids formed during reaction which, if allowed to remain, would decompose the hydroperoxidation products resulting in unwanted by-products. As another example, emulsifiers merely increase the surface area between the gaseous oxygen and the liquid aryl hydrocarbon reactant. Other examples can be cited. As a consequence, the class of materials that are effective hydroperoxidative catalyst is not extensive and is limited generally to phthalocyanines (U.S. Pat. No. 3,873,625), organometallic compounds (U.S. Pat. No. 3,290,384), inorganic compounds (zinc oxide, lead oxide, magnesium oxide, etc.) and certain polymers (U.S. Pat. No. 4,034,047).